A Chinese utility model with patent number 201120264745.0 discloses a water tank inlet valve, which comprises a valve body, a water seal cover, a valve cover, a lever and a float, the valve cover is connected to the valve body and from a valve cavity, the valve body is disposed with a water inlet pipe connected to the valve cavity, the water seal cover is disposed inside the valve cavity, the bottom of the water seal cover is connected to the lever, the lever is connected to the float by an adjusting screw, the water seal cover seals or opens the opening of the water inlet pipe of the valve body under the work of the lever, the top surface of the water seal cover is disposed with a lock element, the lock element is disposed with a boss, a groove is disposed on the top surface and the boss; the top surface of the water seal cover is disposed with a silicone pad, which is sleeved on the lock element; when water flows in through the groove of the boss of the water seal cover, as the silicone pad is thin, under the water stress, the inclined surface between the silicone pad and the water seal cover will be impacted and open a clearance for inlet, the float rises under the work of floatage, it takes the pressure lever to close the small hole of the valve cover, when pressure is large enough to drive the water seal cover to make the silicone pad pressed tightly on the valve body, the inlet valve stops inflowing, meanwhile the dirt and silt are taken away, thus preventing being blocked or a failure of the inlet valve.
Above utility model achieves to close the inlet valve by using the water pressure, however, if it is applied in a toilet water tank that is not sealed, in which water pressure doesn't float much, above utility model will not work, then if the inlet valve is failed, water continuously flows out.